Mesio-Distal Tip and Facio-Lingual Torque Outcomes in Computer-Assisted Orthodontic Treatment

Objective: To investigate the three dimensional outcome root inclination (facio-lingual torque) and angulation (mesio-distal tip) of SureSmileTM (SS) treated cases. Hypothesis: The mean tip and torque discrepancy of the of the SureSmileTM target model (treatment simulation) and the final CBCT (outcome) is not different than the mean tip and torque discrepancy of the initial CBCT and corresponding SureSmileTM therapeutic model (initial model). Methods: Initial SS CBCT (therapeutic or initial CBCT), SS therapeutic model (initial model), post-treatment CBCT (outcome or final CBCT), and SS target model (plan or simulation) were collected for 40 consecutively finished SS cases. DolphinTM 3D root anaylsis software was used to measure the tip and torque values for SS target model and post-treatment CBCT of 30 randomly selected cases. Discrepancies between these variables were compared against the mean discrepancies of the initial CBCT and initial model for 10 randomly selected cases, which was a baseline for expected mean discrepancy of like samples. One sample t-tests were conducted to assess if a difference between tooth tip and torque outcome vs. plan discrepancies were different that found for initial model vs. initial CBCT discrepancies, overall and for each tooth type (i.e. maxillary central incisor, maxillary lateral incisor, etc.). Results: Tests of the final discrepancy to the baseline initial discrepancy were found to be statistically significant for both tip and torque overall, and for many tooth types. Conclusion: Although statically different, the overall mean discrepancy of the SS target models to the outcome CBCT are within clinically acceptable range (±2.5˚). Mean outcome discrepancies were also found to be statistically significant for several tooth types, but clinical significance (beyond ±2.5˚) was limited to the maxillary and mandibular second molars for tip, and the maxillary second molar and mandibular central and lateral for torque. Overall, tip outcomes were closer to the plan than torque outcomes and for most tooth types. The mandibular arch had more teeth with mean discrepancies of statistical significance, fewer outcomes within 2.5˚ of the plan, and had greater overall discrepancy from the plan. Further investigation is necessary to better delineate the cause of these findings.